1. Field of the Invention
This invention comprises a machine and a process for forming crosswise filaments for non-woven fabric. It also comprises crosswise filaments and fabrics made by the process. It has particular application in making crosswise filaments which are self-supporting, as opposed to crosswise filaments which must be held in place by hooks or the like throughout manufacture of a fabric. Self-supporting crosswise filaments can be created by a stand-alone machine and fed to any one of a variety of coaters or lengthwise filament laying machines. Crosswise filaments which are not self-supporting cannot be made by a stand-alone machine but must be made as part of an integrated machine which also lays lengthwise threads.
2. Related Art
A variety of machines have been used or proposed for making non-woven fabrics, and particularly the crosswise filaments for such fabrics. Rotating arm machines such as shown in U.S. Pat. No. 4,108,708 of Gregory lay crosswise filaments into the notches of rotating helixes. As the helixes turn, the crosswise filaments are led into contact with lengthwise filaments to form a fabric. Moving chain machines, such as shown in U.S. Pat. Nos. 4,578,141 of Gidge et al. and 3,345,231 of Gidqe et al., lay crosswise filaments into hooks on chains, which lead those filaments into contact with lengthwise filaments.
The principal problem of these prior art machines and processes has been their complexity. Complexity not only makes them expensive build, but more important, it limits their speed and their ability to make fabric with crosswise filaments of uniform spacing and length. For example, to make a six foot wide fabric in a rotating arm machine, the arm must be over three feet long. In practice, even though these arms rotate at very high velocity, the machines are limited in their lineal output of fabric. Moreover, to double the number of crosswise filaments per inch, one must halve the lineal output of fabric from the machine. In moving chain machines, such as shown in U.S. Pat. No. 4,578,141, the complicated movements needed to lay the filaments on the hooks on the moving chains, and the subsequent movement of the chains to pull the filaments to the full width of the fabric may create entanglement and limit both the speed of the machine and the uniformity of the resulting fabric. Some chain machines, such as shown in U.S. Pat. No. 3,345,231, are capable of high lineal output of fabric, but their crosswise filaments are not self-supporting and cannot produce a fabric with lengthwise filaments perpendicular to crosswise filaments.